Difference Between Obstructive and Restrictive Lung Disease

Obstructive lung diseases feature blocked airways while restrictive lung diseases feature an inability to expand or loss of elastic recoil of lungs. Common obstructive lung diseases are asthma, bronchitis, bronchiectasis and chronic obstructive pulmonary disease (COPD). Common restrictive lung diseases are cystic fibrosis and other causes of pulmonary scarring. Cystic fibrosis shares some features with obstructive lung diseases but is considered a restrictive lung disease according to pathophysiology. Though both obstructive and restrictive lung diseases share some symptoms, signs, diagnosis, and treatment methods, there are slight variations too. This article will talk about those in detail.

What are Obstructive Lung Diseases?

The common obstructive lung diseases are asthma, bronchitis, bronchiectasis, and COPD.

Asthma affects 5-8% of the population. Most asthmatic children grow out of it or suffer much less as adults. It is characterized by recurrent episodes of dyspnea, cough, and wheeze caused by reversible airway obstruction. Three factors contribute to airway narrowing: bronchial muscle contraction triggered by a variety of stimuli, mucosal swelling/inflammation caused by mast cells and basophil degranulation resulting in the release of inflammatory mediators, and increased mucus production. Cold air, exercise, emotion, allergens, infection, and drugs trigger the episodes. Airway diameter changes throughout the day and it is at its smallest during morning and evening. Therefore, most attacks occur during this time of day. Acid reflux is associated with asthma. Spirometry, skin prick test for allergens, and chest x ray are commonly done. Bronchodilators and steroids as inhalers, tablets or, in an emergency, as intravenous preparations may be administered as treatment.

Bronchitis is inflammation of larger airways. It is most commonly viral or bacterial. Patient presents with cough, shortness of breath, sputum production, and sometime fever. There is airway obstruction due to mucus production and bronchial muscle contraction. Bronchitis is treated with steam inhalation, bronchodilators and antibiotics.

Bronchiectasis is due to chronic infections of the bronchi and bronchioles leading to permanent dilatation of these airways. Heamophilus influenza, Streptococcus pneumonia, Staphylococcus aureus and Pseudomonas aeruginosa are the usual culprits. Young syndrome, primary ciliary dyskinesia, cystic fibrosis, Kartergener syndrome, bronchial obstruction due to tumors, and foreign bodies and allergic broncho-pulmonary aspergillosis can lead to bronchiectasis. Bronchiectasis features persistent cough, sputum production, shortness of breath, finger clubbing. It is treated with postural drainage of sputum, antibiotics, bronchodilators and steroids.

Chronic obstructive pulmonary disease (COPD) consists of two closely related clinical entities; chronic bronchitis (long-standing inflammation of large airways characterized by cough and sputum most days of 3 months of two successive years) and emphysema (loss of elastic recoil of lung and histologically,  enlargement of airway smaller than terminal bronchioles and destruction of walls of alveoli). Patients may have either asthma or COPD but not both. If the patient is above 35 years of age, has a history of smoking, long standing production of sputum, cough, shortness of breath without clear variations throughout the day, COPD is likely. NICE (National Institute for Healthcare Excellence) recommends the name COPD. Smoking is the main risk factor for COPD. The tendency to develop COPD rises with the number of cigarettes smoked and all lifelong smokers get COPD.

Individuals who work in gold mines, coal mines, textile plants, may also get COPD due to the chemicals and dust exposure causes an elevated state of reactivity in airways. Similar to cigarette smoke these molecules increase airways secretions and cause constriction of airways. There is no cure for COPD although it is manageable. Acute exacerbations are treated at emergency units with bronchodilators, steroids, and antibiotics.

What are Restrictive Lung Diseases?

The common restrictive lung diseases are cystic fibrosis and other causes of pulmonary scarring.

Cystic fibrosis is one of the commonest life-threatening autosomal recessive conditions affecting Caucasians. It is caused by mutations in the cystic fibrosis trans-membrane conductance regulator gene. This leads to a combination of defective chloride secretion and increased sodium absorption across airway epithelium. The changes in the composition of airway surface liquid predispose the lung to infections and bronchiectasis. Patients present with cough, wheeze, failure to thrive, pancreatic insufficiency, intestinal obstruction, cirrhosis and osteoporosis. Chest physiotherapy, pancreatic enzyme replacement, fat soluble vitamin replacement, and lowering blood sugar are important treatment methods of Cystic fibrosis. Average survival of patients with cystic fibrosis is now over 30 years.

What is the difference between Obstructive and Restrictive Lung Disease?

• Obstructive lung diseases feature airway blockage while restrictive diseases feature a failure of lung expansion.

• In obstructive lung diseases, there is increased mucus formation while there’s none in restrictive diseases.

• Restrictive diseases are due to lung scarring while there is no scarring in obstructive diseases.